Interaction of nanoparticles and cell-penetrating peptides with skin for transdermal drug delivery

Abstract

Topical or transdermal drug delivery is challenging because the skin acts as a natural and protective barrier. Therefore, several methods have been examined to increase the permeation of therapeutic molecules into and through the skin. One approach is to use the nanoparticulate delivery system. Starting with liposomes and other vesicular systems, several other types of nanosized drug carriers have been developed such as solid lipid nanoparticles, nanostructured lipid carriers, polymer-based nanoparticles and magnetic nanoparticles for dermatological applications. This review article discusses how different particulate systems can interact and penetrate into the skin barrier. In this review, the effectiveness of nanoparticles, as well as possible mode of actions of nanoparticles, is presented. In addition to nanoparticles, cell-penetrating peptide (CPP)-mediated drug delivery into the skin and the possible mechanism of CPP-derived delivery into the skin is discussed. Lastly, the effectiveness and possible mechanism of CPP-modified nanocarriers into the skin are addressed.     

Formulation of liposomes gels of paeonol for transdermal drug delivery by Box-Behnken statistical design

The aim of this study was to design and optimize a transdermal liposomes gel formulation for paeonol (PAE). A three-factor, three-level Box-Behnken design was used to derive a second-order polynomial equation to construct three-dimensional (3-D) contour plots for prediction of responses. Independent variables studied were the DC-Chol concentration (X₁), molar ratio of lipid/drug (X₂), and the polymer concentration (X₃), and the levels of each factor were low, medium, and high. The dependent variables studied were the encapsulation efficiency (%EE) of PAE (Y₁), flux of PAE (Y₂), and viscosity of the gels (Y₃). Response surface plots were drawn and statistical validity of the polynomials was established to find the compositions of optimized formulation, which was evaluated using the Franz diffusion cell. The %EE of PAE increased proportionally with the molar ratio of lipid/drug, but decreased with polymer concentration, whereas the flux of PAE increased proportionally with polymer concentration and the DC-Chol concentration. The viscosity of gels increased with the polymer concentration. Gels showed a non-Fickian diffusion release mechanism for PAE, and the in vitro release profiles were fit for Higuchi’s order model. The design demonstrated the role of the derived polynomial equation and 3-D contour plots in predicting the values of dependent variables for the preparation and optimization of gel formulation for transdermal drug release.     

Perspectives on transdermal ultrasound mediated drug delivery

The use of needles for multiple injection of drugs, such as insulin for diabetes, can be painful. As a result, prescribed drug noncompliance can result in severe medical complications. Several noninvasive methods exist for transdermal drug delivery. These include chemical mediation using liposomes and chemical enhancers or physical mechanisms such as microneedles, iontophoresis, electroporation, and ultrasound. Ultrasound enhanced transdermal drug delivery offers advantages over traditional drug delivery methods which are often invasive and painful. A broad review of the transdermal ultrasound drug delivery literature has shown that this technology offers promising potential for noninvasive drug administration. From a clinical perspective, few drugs, proteins or peptides have been successfully administered transdermally because of the low skin permeability to these relatively large molecules, although much work is underway to resolve this problem. The proposed mechanism of ultrasound has been suggested to be the result of cavitation, which is discussed along with the bioeffects from therapeutic ultrasound. For low frequencies, potential transducers which can be used for drug delivery are discussed, along with cautions regarding ultrasound safety versus efficacy.     

Optimization of a jet-propelled particle injection system for the uniform transdermal delivery of drug/vaccine

A jet-propelled particle injection system, the biolistics, has been developed and employed to accelerate micro-particles for transdermal drug delivery. We have examined a prototype biolistic device employing a converging-diverging supersonic nozzle (CDSN), and found that the micro-particles were delivered with a wide velocity range (200-800 m/s) and spatial distribution. To provide a controllable system for transdermal drug delivery, we present a contoured shock-tube (CST) concept and its embodiment device. The CST configuration utilizes a quasi-steady, quasi-one dimensional and shock-free supersonic flow to deliver the micro-particles with an almost uniform velocity (the mean velocity and the standard deviation, 699 +/- 4.7 m/s) and spatial distribution. The transient gas and particle dynamics in both prototype devices are interrogated with the validated computational fluid dynamics (CFD) approach. The predicted results for static pressure and Mach number histories, gas flow structures, particle velocity distributions and gas-particle interactions are presented and interpreted. The implications for clinical uses are discussed.     

Nanoemulsions as vehicles for transdermal delivery of aceclofenac

The aim of the present study was to investigate the potential of a nanoemulsion formulation for transdermal delivery of aceclofenac. Various oil-in-water nanoemulsions were prepared by the spontaneous emulsification method. The nanoemulsion area was identified by constructing pseudoternary phase diagrams. The prepared nanoemulsions were subjected to different thermodynamic stability tests. The nanoemulsion formulations that passed thermodynamic stability tests were characterized for viscosity, droplet size, transmission electron microscopy, and refractive index. Transdermal permeation of aceclofenac through rat abdominal skin was determined by Franz diffusion cell. The in vitro skin permeation profile of optimized formulations was compared with that of aceclofenac conventional gel and nanoemulsion gel. A significant increase in permeability parameters such as steady-state flux (J(ss)), permeability coefficient (K(p)), and enhancement ratio (E(r)) was observed in optimized nanoemulsion formulation F1, which consisted of 2% wt/wt of aceclofenac, 10% wt/wt of Labrafil, 5% wt/wt of Triacetin, 35.33% wt/wt of Tween 80, 17.66% wt/wt of Transcutol P, and 32% wt/wt of distilled water. The anti-inflammatory effects of formulation F1 showed a significant increase (P < .05) in percent inhibition value after 24 hours when compared with aceclofenac conventional gel and nanoemulsion gel on carrageenan-induced paw edema in rats. These results suggested that nanoemulsions are potential vehicles for improved transdermal delivery of aceclofenac.     

Phosphatidyl choline-based colloidal systems for dermal and transdermal drug delivery

In this study we have prepared various phosphatidyl choline based colloidal systems, namely liposomes, transfersomes, microemulsions and micelles, using similar excipients and compared their ability to deliver drugs into and through the skin under occlusive and non-occlusive conditions. Hydrophilic propranolol hydrochloride (PHCl) and lipophilic propranolol base (PB) were used as model drugs. All tested parameters, that is formulation composition, drug characteristics and testing conditions, influenced skin permeability and skin retention. A trend was observed showing that the skin permeation as well as skin retention decreases with the amount of phosphatidyl choline in the formulations for both tested model drugs (micelles > transfersomes > liposomes > microemulsion). The lipophilic model drug had higher skin permeability especially when incorporated into the systems containing mainly hydrophilic excipients. Skin retention, however, was not affected by the drug hydrophilicity to the same extent as skin permeability. Occlusion increased both skin retention and skin permeation for both model drugs.     

Biotin and glucose dual-targeting,ligand-modified liposomes promote breast tumor-specific drug delivery

Breast cancer is the second leading cause of cancer-related deaths in women. Ligand-modified liposomes are used for breast tumor-specific drug delivery to improve the efficacy and reduce the side effects of chemotherapy; however, only a few liposomes with high targeting efficiency have been developed because the mono-targeting, ligand-modified liposomes are generally unable to deliver an adequate therapeutic dose. In this study, we designed biotin-glucose branched ligand-modified, dual-targeting liposomes (Bio-Glu-Lip) and evaluated their potential as a targeted chemotherapy delivery system in vitro and in vivo. When compared with the non-targeting liposome (Lip), Bio-Lip, and Glu-Lip, Bio-Glu-Lip had the highest cell uptake in 4T1 cells (3.00-fold, 1.60-fold, and 1.95-fold higher, respectively) and in MCF-7 cells (2.63-fold, 1.63-fold, and 1.85-fold higher, respectively). The subsequent cytotoxicity and in vivo assays further supported the dual-targeting liposome is a promising drug delivery carrier for the treatment of breast cancer.     

Small liposomes are better than large liposomes for specific drug delivery in vitro

We have compared drug transfer into target cells in vitro from liposomes of different sizes. Liposomes of mean diameter 800 Å, 2000 Å or 4000 Å, containing the folate analogue, methotrexate, and the fluorophore, carboxyfluorescein, were covalently coupled to Staphylococcus aureus protein A. Cells of the murine k haplotype were preincubated with an anti-H-2K^k monoclonal antibody. Excess antibody was removed and then cells were incubated with liposomes. The number of cell-bound liposomes was determined by fluorimetry. The drug effect was assayed by the methotrexate-mediated inhibition of radiolabeled deoxyuridine uptake. The drug effect was more important in the case of the 800 Å vesicles than for the larger liposomes, despite the fact that the quantity of drug bound to cells was several-fold greater for large liposomes than for small ones. Since fusion is excluded by the non-proportionality of drug binding and drug effect, the predominant manner of liposome entry seems to be endocytosis. At least for these in vitro studies, the endocytosis by target cells of small liposomes seems to be more efficient than that of large liposomes.     

Evaluation of polymerized rosin for the formulation and development of transdermal drug delivery system: A technical note

Conclusions  Results from the present study conclude that PR in combination with PVP and with incorporation of dibutyl phthalate (30% wt/wt) produces smooth flexible films with improved tensile strength and percentage elongation. The release rate of drug from films and permeation across skin increases with increase in drug and PVP loading but is independent of film thickness. Patches containing PR:PVP (7:3) show promise for pharmacokinetic and pharmacodynamic performance evaluation in a suitable animal model. In view of the overall results reported in the present study, it may be proposed that PR can be used in the design of a matrix type transdermal drug delivery system to prolong the drug release. Published: December 27, 2005     

Nano-proniosomes enhancing the transdermal delivery of mefenamic acid

Mefenamic acid (MA) is a BCS II class NSAID drug. It is available only in the form of tablets, capsules, and pediatric suspensions. Oral administration of MA is associated with severe gastrointestinal side effects. The aim of this study was to develop a convenient and low-cost transdermal drug delivery system for MA using proniosome as a novel carrier without the addition of penetration enhancers. The formulation factors, such as the presence of cholesterol, types of lecithin, and surfactants were investigated for their influence on the entrapment efficiency, rate of hydration, vesicle size, and zeta potential, in vitro drug release and skin permeation in order to optimize the proniosomal formulations with the minimum dose of the drug. Furthermore, the in vivo anti-inflammatory effect was evaluated on a formalin-induced rat paw edema model. The results showed that the type of surfactants had higher impact on the entrapment efficiency than the type of lecithins, with the highest in Span 80 (82.84%). The release of MA from Span 80 proniosomal gel was significantly affected by the type of lecithin used. The addition of cholesterol significantly increased both the drug release and the skin permeation flux of MA. Zeta potential showed a stable A4 noisomal suspension. DSC revealed the molecular dispersion of MA into the loaded proniosomes. In vivo study of the treatment group with MA proniosome gel showed a significant inhibition of rat paw edema compared with the same gel without the drug (control). The results of this study suggest that proniosomes are promising nano vesicular carriers and safe alternatives to enhance the transdermal delivery of MA.     

Evaluation of alternative strategies to optimize ketorolac transdermal delivery

In the present study, 2 alternative strategies to optimize ketorolac transdermal delivery, namely, prodrugs (polyoxyethylene glycol ester derivatives, I–IV) and nanostructured lipid carriers (NLC) were investigated. The synthesized prodrugs were chemically stable and easily degraded to the parent drug in human plasma. Ketorolac-loaded NLC with high drug content could be successfully prepared. The obtained products formulated into gels showed a different trend of drug permeation through human stratum corneum and epidermis. Particularly, skin permeation of ester prodrugs was significantly enhanced, apart from ester IV, compared with ketorolac, while the results of drug release from NLC outlined that these carriers were ineffective in increasing ketorolac percutaneous absorption owing to a higher degree of mutual interaction between the drug and carrier lipid matrix. Polyoxyethylene glycol esterification confirmed to be a suitable approach to enhance ketorolac transdermal delivery, while NLC seemed more appropriate for sustained release owing to the possible formation of a drug reservoir into the skin. Published: August 4, 2006     

Dual-targeting for brain-specific liposomes drug delivery system: Synthesis and preliminary evaluation

The treatment of glioma has become a great challenge because of the existence of brain barrier (BB). In order to develop an efficient brain targeting drug delivery system to greatly improve the brain permeability of anti-cancer drugs, a novel brain-targeted glucose-vitamin C (Glu-Vc) derivative was designed and synthesized as liposome ligand for preparing liposome to effectively deliver paclitaxel (PTX). The liposome was prepared and its particle size, zeta potential, encapsulation efficiency, release profile, stability, hemolysis and cytotoxicity were also characterized. What’s more, the cellular uptake of CFPE-labeled Glu-Vc-Lip on GLUT₁- and SVCT₂-overexpressed C6 cells was 4.79-, 1.95-, 4.00- and 1.53-fold higher than that of Lip, Glu-Lip, Vc-Lip and Glu?+?Vc-Lip. Also, the Glu-Vc modified liposomes showed superior targeting ability in vivo evaluation compared with naked paclitaxel, non-coated, singly-modified and co-modified by physical blending liposomes. The relative uptake efficiency was enhanced by 7.53 fold to that of naked paclitaxel, while the concentration efficiency was up to 7.89 times. What’s more, the Glu-Vc modified liposomes also displayed the maximum accumulation of DiD-loaded liposomes at tumor sites with the strongest fluorescence in the brain in vivo imaging. Our results suggest that chemical modification of liposomes with warheads of glucose and vitamin C represents a promising and efficient strategy for the development of brain-specific liposomes drug delivery system by utilizing the endogenous transportation mechanism of the warheads.     

In vivo characterization of monolithic matrix type transdermal drug delivery systems of pinacidil monohydrate: A technical note

Summary and Conclusions  The present work aimed to characterize transdermal drug delivery systems of pinacidil monohydrate in vivo by monitoring the effect of the TDDS on blood pressure of methyl prednisolone acetate induced hypertensive rats. The blood pressure of rats was measured using a noninvasive rat BP instrument based on cuff tail technique. A significant fall in rat BP (P<.01) was observed in treatment of hypertensive rats with all the formulations, which was maintained for 48 hours. Interformulation comparison revealed that formulation B-4 was the most effective with 37.96% reduction in BP (160.33±4.96 vs 99.44±4.46 mmHg). It was concluded that a single patch application of pinacidil TDDS (B-4) can effectively control hypertension in rats for 2 days. The system holds promise for clinical studies. Publised: January 13, 2006     

Bioinspired polymers that control intracellular drug delivery

One of the important characteristics of biological systems is their ability to change important properties in response to small environmental signals. The molecular mechanisms that biological molecules utilize to sense and respond provide interesting models for the development of “smart” polymeric biomaterials with biomimetic properties. An important example of this is the protein coat of viruses, which contains peptide units that facilitate the trafficking of the virus into the cell via endocytosis, then out of the endosome into the cytoplasm, and from there into the nucleus. We have designed a family of synthetic polymers whose compositions have been designed to mimic specific peptides on viral coats that facilitate endosomal escape. Our biomimetic polymers are responsive to the lowered pH within endosomes, leading to disruption of the endosomal membrane and release of important biomolecular drugs such as DNA, RNA, peptides and proteins to the cytoplasm before they are trafficked to lysosomes and degraded by lysosomal enzymes. In this article, we review our work on the design, synthesis and action of such smart, pH-sensitive polymers.     

Proultraflexible lipid vesicles for effective transdermal delivery of levonorgestrel: Development,characterization, and performance evaluation

The present investigation aimed at formulation, performance evaluation, and stability studies of new vesicular drug carrier system protransfersomes for transdermal delivery of the contraceptive agent, levonorgestrel. Protransfersome gel (PTG) formulations of levonorgestrel were prepared and characterized for vesicle shape, size, entrapment efficiency, turbidity, and drug permeation across rat skin and were evaluated for their stability. The system was evaluated in vivo for biological assay of progestational activity including endometrial assay, inhibition of the formation of corpora lutea, and weight gain of uterus. The effects of different formulation variables (type of alcohol, type and concentration of surfactant) on transdermal permeability profile were assessed. The optimized PTG formulation showed enhanced in vitro skin permeation flux of 15.82±0.37 μg/cm²/hr as compared to 0.032±0.01 μg/cm²/hr for plain drug solution. PTG also showed good stability and after 2 months of storage there was no change in liquid crystalline nature, drug content, and other characteristic parameters. The peak plasma concentration of levonorgestrel (0.139±0.05 μg/mL) was achieved within 4 hours and maintained until 48 hours by a single topical application of optimized PTG formulation. In vivo performance of the PTG formulation showed increase in the therapeutic efficacy of drug. Results indicated that the optimized protransfersomal formulation of levonorgestrel had better skin permeation potential, sustained release characteristic, and better stability than proliposomal formulation.     

Lecithin soybean phospholipid nano-transfersomes as potential carriers for transdermal delivery of the human growth hormone

Pharmaceutical molecules such as peptides and proteins are usually injected into the body. Numerous efforts have been made to find new noninvasive ways to administer these peptides. In this study, highly flexible vesicles (transfersomes [TFs]) were designed as a new modern transdermal drug delivery system for systemic drug administration through the skin, which had also been evaluated in vitro. In this study, two growth hormone-loaded TF formulations were prepared, using soybean lecithin and two different surfactants; F₁_sodium deoxycholate and F ₂_sodium lauryl sulfate. Thereafter, the amount of skin penetration by the two formulas was assessed using the Franz diffusion cell system. TF formulations were evaluated for size, zeta potential and in vitro skin penetration across the rat skin. Results indicated that vesicle formulations were stable for 4 weeks and their mean sizes were 241.33 ± 17 and 171 ± 12.12 nm in the F ₁ and F ₂ formulation, respectively. After application to rat skin, transport of the human growth hormone (hGH) released from the TF formulations was found to be higher than that of the hGH alone. Maximum amounts of transdermal hormone delivery were estimated to be 489.54 ± 8.301 and 248.46 ± 4.019 ng·cm−2 , for F ₁ and F ₂, respectively. The results demonstrate the capability of the TF-containing growth hormone in transdermal delivery and superiority of the F ₁ to F ₂ TFs.     

Development of wrapped liposomes: Novel liposomes comprised of polyanion drug and cationic lipid complexes wrapped with neutral lipids

Novel wrapped liposomes comprised of polyanion drug and cationic lipid complexes wrapped with neutral lipids were prepared using an efficient, innovative procedure. In this study, dextran fluorescein anionic (DFA) was used as an example of a polyanionic compound. During the process, neutral lipids accumulated around the complexes and eventually covered the complexes. The resulting liposomes were 120-140 nm in diameter and the encapsulation efficiency was up to 90%. In fetal bovine serum, DFA/cationic lipid complexes degraded rapidly but the wrapped liposomes were considerably more stable. Following intravenous administration to rats, DFA/cationic lipid complexes were rapidly eliminated whereas the wrapped liposomes exhibited a much longer blood half-life. These data suggest that DFA is located on the surface of the complexes, but DFA is present inside the wrapped liposomes. The drug-delivery properties of the wrapped liposomes established in the present study suggests that formulations based on this technology could offer important advantages for the administration of many types of drug including antisense oligonucleotides, plasmids and siRNAs which may therefore lead to improved therapeutic effectiveness of this range of drugs. The method of preparation of the wrapped liposomes is so simple that it should be straightforward to adapt to a manufacturing scale.     

Characterization of a novel pH-sensitive peptide that enhances drug release from folate-targeted liposomes at endosomal pHs

Although liposomes have proven useful for the delivery of drugs and gene therapy vectors, their potencies are often compromised by poor unloading following uptake into their target cells. We have consequently explored the properties of a novel 29-residue amphipathic peptide that was designed by arrangement of hydrophobic and hydrophilic residues to disrupt liposomes at lower peptide concentrations than previously tested peptides. The peptide was indeed found to promote pH-dependent liposome unloading with improved efficiency. A peptide of the same sequence, but half the length, however, promoted pH-dependent permeabilization only at much higher concentrations. Further characterization of the longer peptide revealed that release of liposome contents (i) occurred at a pH of ∼6, (ii) became less efficient as the size of the encapsulated cargo increased, and (iii) was moderately suppressed in cholesterol-containing liposomes. Use of this peptide to enhance the cytotoxicity of cytosine arabinoside encapsulated in folate-targeted liposomes demonstrated an increase in drug potency of ∼30-fold. Gene expression by a serum-stable folate-targeted liposomal vector was also measurably enhanced by inclusion of the peptide. We conclude that intracellular unloading of liposomal contents can be significantly improved by co-encapsulation of an optimally designed, pH-sensitive peptide.     

Investigating superiority of novel bilosomes over niosomes in the transdermal delivery of diacerein: in vitro characterization,ex vivo permeation and in vivo skin deposition study

Skin is considered the most accessible organ of the body because of its underlying capillary network. However, stratum corneum (SC), the upper most layer of skin, represents major diffusional barrier for most drugs. Hence, the use of edge activators (EAs) in designing novel elastic vesicles is hypothesized to impart their lipid bilayer with ultra-flexibility to trespass SC by high self-optimizing deformability. To confirm this hypothesis, this work aimed at developing novel bilosomes by modulating conventional niosomal composition using different bile salts as EAs and investigating their superiority over niosomes for transdermal delivery of diacerein (DCN), as model drug. Bilosomes were prepared by thin film hydration (TFH) technique according to full 3¹.2² factorial design to select the optimal formulation using Design-Expert^® software. The optimal bilosomes (B6) showed nanosized vesicles (301.65?±?17.32?nm) and 100.00?±?0.00 % entrapment efficiency. Ex vivo permeation studies and in vivo evaluation revealed that B6 exhibited superior permeation and drug retention capacity compared to the conventional niosomal formulation and drug suspension. Furthermore, B6 was subjected to in vivo histopathological study using male Wistar rats which ensured its safety for topical application. Overall, the results confirmed the hypothesized superiority of bilosomes over niosomes for enhancing DCN flux across the skin.     

Interaction of nanoparticles and cell-penetrating peptides with skin for transdermal drug delivery

Topical or transdermal drug delivery is challenging because the skin acts as a natural and protective barrier. Therefore, several methods have been examined to increase the permeation of therapeutic molecules into and through the skin. One approach is to use the nanoparticulate delivery system. Starting with liposomes and other vesicular systems, several other types of nanosized drug carriers have been developed such as solid lipid nanoparticles, nanostructured lipid carriers, polymer-based nanoparticles and magnetic nanoparticles for dermatological applications. This review article discusses how different particulate systems can interact and penetrate into the skin barrier. In this review, the effectiveness of nanoparticles, as well as possible mode of actions of nanoparticles, is presented. In addition to nanoparticles, cell-penetrating peptide (CPP)-mediated drug delivery into the skin and the possible mechanism of CPP-derived delivery into the skin is discussed. Lastly, the effectiveness and possible mechanism of CPP-modified nanocarriers into the skin are addressed.